【作者】 王峰凌；

【导师】 卢新卫；

【作者基本信息】 陕西师范大学 ， 第四纪地质， 2008， 硕士

【摘要】 煤炭为社会经济发展做出巨大贡献的同时也带来了严重的环境污染问题。煤炭燃烧过程中，煤中的放射性核素会在煤灰和煤渣中残留富集，进而随煤灰、灰渣进入周边土壤，影响土壤放射性水平。陕西省内煤炭资源丰富，燃煤电厂较多，燃煤固体废弃物排放量大，而燃煤电厂固废的环境辐射影响研究极为欠缺。本研究在辐射监测与防护方面具有重要的理论与现实意义。本文以西安两大燃煤电厂（灞桥和西郊热电厂）为研究对象，应用低本底伽玛能谱法分析燃煤电厂原煤、煤灰、炉渣以及电厂、储灰场周边土壤中的放射性核素含量，了解煤炭燃烧过程中核素的迁移富集特征，分析燃煤电厂对环境的辐射影响以及电厂固废建材使用的辐射暴露。研究结果显示，西郊和灞桥电厂周边土壤本底较低，在长期生产过程中由于飞灰释放沉积，电厂周边土壤表层中放射性核素²²⁶Ra含量显著增加，储灰场对周围环境的辐射影响更加明显。西郊和灞桥电厂灰渣使用过程中，要注意其带来的额外辐射，防止居民健康受到影响。本论文的主要结论如下：1．西郊热电厂原煤中²²⁶Ra平均含量为16．2 Bq／kg，²³²Th平均含量为28．0 Bq／kg，⁴⁰K平均含量为49．6 Bq／kg。（西郊热电厂）煤灰中²²⁶Ra平均含量为59．2 Bq／kg，²³²Th平均含量为72 Bq/kg，⁴⁰K平均含量为250．1 Bq／kg。（西郊热电厂）炉渣中²²⁶Ra平均含量53．5 Bq／kg，²³²Th平均含量为49．7 Bq／kg，⁴⁰K平均含量为214．4 Bq／kg。（西郊热电厂）煤灰中²²⁶Ra含量为原煤的3．7倍，²³²Th含量为原煤的2．6倍，⁴⁰K含量为原煤的5．0倍；（西郊热电厂）炉渣中²²⁶Ra含量为原煤的3．3倍，²³²Th含量为原煤的1．8倍，⁴⁰K含量为原煤的4．3倍。（西郊热电厂）煤灰中天然放射性核素²²⁶Ra富集度为0．725，²³²Th富集度为0．881。（西郊热电厂）炉渣中为²²⁶Ra富集度为0．761，²³²Th富集度为0．707。大量使用西郊电厂煤灰作为建筑材料，将导致建筑物室内空气吸收剂量率增加0．458×10^-8 Gy／h；长期居住在使用西郊电厂灰渣建材的房屋内，居民受到的年有效剂量当量为0．074 mSv。2．西郊热电厂周边1公里范围内，表层土壤中²²⁶Ra含量平均为31．46 Bq／kg，B和C层中²²⁶Ra平均含量分别为24．85 Bq／kg和25．70 Bq／kg，土壤²²⁶Ra本底为25±1 Bq／kg；²³²Th和⁴⁰K含量与陕西省土壤平均含量接近。电厂周围土壤1m高处空气γ平均剂量率为56．4 nGyh^-1；电厂周围土壤表层等效镭浓度平均为128．74 Bq／kg。西郊电厂周边土壤中天然放射性核素产生的陆地γ辐射对周围居民产生的年有效剂量当量为0．550 mSv。3．灞桥热电厂原煤中²²⁶Ra平均含量为36．56 Bq／kg，²³²Th平均含量为36．08 Bq／kg，⁴⁰K平均含量为88．55 Bq/kg，灞桥电厂原煤天然放射性核素含量与全国平均含量相比较低。（灞桥热电厂）灰渣中²²⁶Ra平均含量为55．18 Bq／kg，²³²Th平均含量为65．15 Bq／kg，⁴⁰K平均含量为242．84 Bq/kg。（灞桥热电厂）灰渣中²²⁶Ra含量为原煤的1．5倍，²³²Th含量为原煤的1．8倍，⁴⁰K含量为原煤的2．74倍。（灞桥热电厂）灰渣中²²⁶Ra富集度为0．550，²³²Th富集度为0．658。使用灞桥电厂灰渣作为建筑材料，将导致建筑物室内空气吸收剂量率增加0．423×10^-8Gy／h，灞桥电厂灰渣建材给居民带来的年有效剂量当量为0．060 mSv。4．灞桥热电厂周边1公里范围内，表层土壤中²²⁶Ra含量平均为36．57 Bq/kg；电厂周边土壤中²²⁶Ra本底为26±1 Bq/kg，低于陕西省土壤²²⁶Ra含量平均值，²³²Th和⁴⁰K含量与陕西省土壤平均含量接近。灞桥电厂周围土壤1m高处空气γ平均剂量率为58．3 nGyh^-1，电厂周边表层土壤等效镭浓度平均为133．82 Bq/kg，陆地γ辐射对周围居民产生的年有效剂量当量为0．552 mSv。5．灞桥热电厂储灰场周围1公里范围内，表层土壤中²²⁶Ra含量平均为42．83 Bq／kg；储灰场周围土壤中²²⁶Ra本底为26±1 Bq／kg，低于陕西省土壤中²²⁶Ra平均含量；土壤样品中²³²Th平均含量均低于陕西土壤平均值；⁴⁰K含量范围为200．83-673．16 Bq／Kg。储灰场周边土壤1m高处空气γ平均剂量率为58．8 nGyh^-1，储灰场周边表层土壤等效镭浓度平均为136．70 Bq／kg，储灰场周围陆地γ辐射对周围居民产生的年有效剂量当量为0．553 mSv。更多还原

【Abstract】 Coal has made great contribution for the socio-economic development but also brought serious environmental pollution problems. Combustion of coal in the course of the radionuclides in coal ash and cinder in the enrichment of the residue, then with ash, the ash into the soil, affecting the level of radioactive soil. The resource of coal is abundant in Shaanxi Province. There are a lot of coal-fired power plants, which have brought a mass of solid waste every year, but the study about the radioactive influence of solid waste is extremely deficient. This research has great theoretical and practical significance in the radioactive radiation monitoring and protection.In this paper, two coal-fired power plants in Xi’an for the study, application of the low end of gamma spectroscopy analysis the coal, the ash, the slag of coal-fired thermal power plant and the soil around coal-fired power plants. It has studied the process of transfer and enrichment of radionuclides, researched the environmental radioactive influence of the two coal-fired power plants and the solid waste that using as structural material.The results showed that in the long-term production process of power plant, due to the release of fly ash deposition, contents of natural radioactive nuclides increased obviously in the surface soil around coal-fired power plant. We should bring additional attention to the radiation of solid waste that using as structural material to prevent the health of denizen was affected. The main conclusions were listed below:1. In the residue of Xijiao coal-fired power plant, the average of radionuclide concentration is 16.2 Bq/kg for ²²⁶Ra, 28.0 Bq/kg for ²³²Th, 49.6 Bq/kg for ⁴⁰K in the coal and 59.2 Bq/kg for ²²⁶Ra, 72.0 Bq/kg for ²³²Th, 250.1 Bq/kg for ⁴⁰K in the ash and 53.5 Bq/kg for ²²⁶Ra, 49.7 Bq/kg for²³²Th, 214.4 Bq/kg for ⁴⁰K. After the coal is burnt, the mean concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the ash is 3.7, 2.6 and 5.0 times of the coal and in the residue is 3.3, 1.8 and 4.3 times of the coal. The enrichment factor of ²²⁶Ra, ²³²Th is 0.761 and 0.707. The absorb dose rate increase 0.458×10^-8 Gy/h while using the ash of Xijiao coal-fired power plant as architectural material. The effective dose rate is 0.074 mSv every year.2. The mean natural radionuclide concentration is 31.46 Bq/kg for ²²⁶Ra in horizon A, 24.85 Bq/kg for ²²⁶Ra in horizon B, 25.70 Bq/kg for ²²⁶Ra in horizon C and the background of ²²⁶Ra is 25±1 Bq/kg in soil around Xijiao coal-fired plant. The total gamma dose rate in air at 1 m above the ground is 56.4 nGyh^-1; the average radium equivalent activity is 128.74 Bq/kg around Xijiao coal-fired plant; the average annual effective dose rate is 0.550 mSv.3. The mean natural radionuclide concentration is 36.56 Bq/kg for ²²⁶Ra, 36.08 Bq/kg for ²³²Th, 88.55 Bq/kg for ⁴⁰K in the coal and 55.18 Bq/kg for ²²⁶Ra, 65.15 Bq/kg for ²³²Th, 242.84 Bq/kg for ⁴⁰K in the ash and residue of Baqiao coal-fired power plant. After the coal is burnt, the mean concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the ash is 1.5, 1.8 and 2.7 times of the coal and in the residue is 3.3, 1.8 and 4.3 times of the coal. The enrichment factor of ²²⁶Ra, ²³²Th is 0.550 and 0.658. The absorb dose rate increase 0.423×10^-8 Gy/h while using the ash of Baqiao coal-fired power plant as architectural material. The effective dose rate is 0.060 mSv every year.4. The mean natural radionuclide concentration is 36.57 Bq/kg for ²²⁶Ra in horizon A and the background of Ra is 26±1 Bq/kg in soil around Baqiao coal-fired plant. The total gamma dose rate in air at 1 m above the ground is 58.3 nGyh^-1; the average radium equivalent activity is 133.82 Bq/kg around Baqiao coal-fired plant; the average annual effective dose rate is 0.552 mSv.5. The mean natural radionuclide concentration is 42.83 Bq/kg for ²²⁶Ra in horizon A and the background of ²²⁶Ra is 26±1 Bq/kg in soil around Baqiao coal-fired plant. The total gamma dose rate in air at 1m above the ground is 58.3 nGyh^-1; the average radium equivalent activity is 136.70 Bq/kg around Baqiao coal-fired plant; the average annual effective dose rate is 0.552 mSv.更多还原